Miranda ("mi RAN duh") is the eleventh of Uranus's known satellites. Miranda is the innermost of Uranus' large moons.

orbit: 129,850 km from Uranus diameter: 472 km mass: 6.3e19 kgMiranda is a daughter of the magician Prospero in Shakespeare's The Tempest. Discovered by Kuiper in 1948.

Voyager 2 was forced to fly close to Uranus in order to get the boost it needed to go on to Neptune and due to the orientation of the whole system at almost right angles to the ecliptic only Miranda was approached closely. Before Voyager, of course, little was known about Miranda and as it is not the largest or in any other way remarkable, it probably would not have been chosen as the prime target at Uranus. Voyager's good luck held up, however, as Miranda turned out to be by far the most interesting.

Miranda is about half water ice and half rocky material.

Miranda's surface is all mixed up with heavily cratered terrain intermixed with weird grooves, valleys and cliffs (one over 5 kilometers high; left).

At first, Voyager 2's images of Miranda were a mystery. Everyone had expected that Uranus' moons would show very little history of internal activity (like Callisto). Explaining the bizarre hitherto unknown terrain proved quite an embarrassment to those who had to do it on live TV. Their usual impressive and esoteric technical jargon gave out and they had to resort to using such terms as "chevron" (right), "race track", and "layer cake" to describe Miranda's unique features.

It was initially thought that Miranda had been completely shattered and reassembled several times in its history, each time burying some parts of the original surface and exposing some of the interior. Now, however, a more mundane explanation involving the upwelling of partially melted ices seems to be in favor.

Open IssuesThe upwelling and shattering explanations for Miranda's bizarre appearance are really just speculation. Much more evidence is needed to provide a satisfactory explanation. There are no more missions planned to Uranus and Neptune. When will we next visit to this peculiar world? The data from Voyager 2 may be all we have for a very long time.

How could the moons of Uranus be distributed in such circular, evenly spaced orbits around Uranus' equator when Uranus' equator is so glaringly out-of-sync with the rest of the solar system? The same electric forces that give birth to planets and moons are also responsible for circularizing their orbits.

The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.

Miranda displays a dramatically varied surface. Easy to see in this 660m (2160 ft) wide image are numerous ridges and valleys -- a topography that was probably produced by compressional tectonics. Cutting across Miranda's ridges and valleys are many faults. The largest fault scarp is seen below and right of center; it shows grooves probably made by the fault blocks as they rubbed against each other (leaving what are known as slickensides). Movement of the down-dropped block is shown by the offset of the ridges. The fault may be 5 km (3 mi) high, or higher than the walls of the Grand Canyon on Earth.

The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.

Miranda's South PoleThe Chevron is an unusual feature on the surface of Miranda. The small number of craters indicates that this extensive system of faults is younger than the surrounding heavily cratered terrain. Some of the dark material inside the Chevron may be igneous material ejected along the fault planes. The lower image offers a perspective view of the same region shown in the top. It was generated from a computer model of the surface topography. The relief is exaggerated by about 50- fold; the view angle is about 15 degrees above the horizon.

The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.

Miranda is unique among the uranian satellites but, excepting its much smaller size, strongly resembles Ganymede in the Jovian group. By serendipity, Voyager 2 made the closest approach to Miranda of any of the satellites, so it could image the peculiar terrains in detail. Investigators based this flyby decision on the need to use this satellite to give the spacecraft a gravitational boost towards Neptune. First, look at the full view (left), a mosaic of one face. Then (right), view a close-up of the surface.

Two sharply contrasting terrains are evident. Much of Miranda's surface consists of rather bright, heavily cratered terrains, similar to the above four satellite exteriors. But there are three large oval-to-rectangular terrains (called coronae), whose physiographies are quite different (to each other and to the dominant terrain). They may contain subparallel grooves, several as deep as 2 km (1.2 mi), or alternating light-dark bands, or ridges and stripes that take sharp bends. A closer view (at bottom, above) of ridged terrain shows the generally abrupt boundaries of these terrains with the encompassing older terrain. Scientists still debate the origin of these patches. An early interpretation considered them to be fragments of a shattered proto-Miranda or some other disrupted satellite, incorporated in a re-assembling satellite. The paucity of craters in these isolated terrains argues against this.Another opinion holds them to be a mix of rock and ice that formed a crust, which broke up and was invaded by upwelled ice masses from the interior.

19-70: Develop an argument against the impact disruption hypothesis. ANSWER 19-70: One can go either way on this concept. If an impact completely disrupted an earlier satellite, chances are it would be fragmented mainly into small pieces so that the corona terrains would not be as large as they are. But, these terrains may have been spallation blocks that stayed intact. Just how they then would reassemble as we seen them is not clear.

The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.

Miranda: shattering an old image - coronas of Uranus' Miranda formed when internal forces pulled the satellite apart

Researchers initially proposed that the rough-hewn surface formed because Miranda, after being struck by a comet or other large object early in the history of the solar system, shattered and then influence of Uranus' gravity. That scenario has appeared in several textbooks as well as popular accounts of Mirandahs evolution. But in reanalyzing the Voyager images, Robert T. Pappalardo, Ronald Greeley, and Stephen J. Reynolds of Arizona State University in Tempe say they have found evidence to demolish that notion.

Pappalardo and others note that if the breakup theory were correct, the moon's rocky, denser chunks would have sunk toward the reassembled core if the satellite. Internal currents created by the sinking would have formed the coronas by compressing the surface, and the ridges and troughs would represent compressional folds within the coronas. But when he and his colleagues exmained the Voyager images using a filter that highlighted Miranda's unusual topography, they found no evidence of compression.Instead, says Pappalardo, the coronas appear to have formed atop giant upwellings of material from the moon's interior. The alternating ridges anf troughs were created when internal forces pulled the surface apart--in much the same way that such features were formed in the American Soutwest and on Jupiter's moon Ganymede, he notes.Images of Miranda's Arden and Inverness coronas indicate that giant blocks material, some more than 10 kilometers dominoes to create fault scraps, Pappalardo says. He suggests that tidal stretching and distortion by Uranus' gravity could have supplied the heat source necessary to fuel such uprisings.

The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.

Craters are formed on an airless world like Miranda when small chunks of material coming from space hit the moon and blast a hole on impact. The longer a particular piece of ground has remained unchanged, the longer it has served as a target for craters. In fact, most of Miranda's surface is made of old rolling terrain, with many craters dotting the landscape. For some reason we don't understand, the regions like the checkmark must have formed or changed later in Miranda's history.

Miranda also has vast cracks in the surface where the land seems to have shifted, exposing giant cliffs that would put many a mountain cliff on Earth to shame. The most impressive of these cliffs towers some 6 to 9 miles above its valley floor. (Compare this to the Grand Canyon in Arizona, which is only about a mile deep.) Furthermore, gravity is so weak on this little world that if you were to drop a rock from Miranda's tallest cliff, it would take a full five minutes to reach the bottom.

Interestingly enough, Voyager 2 only saw half of Miranda — the hemisphere illuminated by the Sun. Like Uranus, Miranda was tilted so its South Pole was pointed directly toward the Sun as Voyager passed. Thus our brief glimpse was only of its Southern Hemisphere. We can only wonder what sights await us on the other half of the satellite.

At the very least, Miranda teaches us that we cannot take anything for granted when we look at a planet or satellite for the first time.

The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.

This image of Uranus, its ring system, and two of its satellites Miranda (top-center) and Ariel (bottom-left) is from Subaru Telescope's Coronagraphic Imager with Adaptive Optics (CIAO) combined with Subaru Telescope's adaptive optics system (AO).

On March 13, 1781, British astronomer William Herschel discovered an object that appeared large compared to a star during observations with a homemade 6.3 inch (16 cm) telescope. The object, which was initially thought to be a comet, turned out to be a new planet outside Saturn's orbit, and was named Uranus.

Uranus revolves around the Sun in approximately 84 years on an elliptic orbit whose average radius is approximately 1.7 billion miles (2.8 billion kilometers). Unlike other planets, Uranus spins on its side with respect to its orbital plane. Since 1851, over 10 satellites and 10 rings have been discovered around Uranus.

This image was taken during tests of the combined use of CIAO and AO in July 2001. It combines near-infrared images in three different filters, so the colors are not the same as what we would see in the optical. In this color scheme, methane, the dominant component of Uranus's atmosphere, shows up as blue.

Scientists from several research institutes and universities, in addition to the National Astronomical Observatory of Japan, participated in the development of CIAO and Subaru Telescope's AO system. The team from Kobe University processed this image.

The image was first introduced to the public in a Japanese television program "Youkoso Senpai" ("Welcome back Graduate!") by the Japan Broadcasting Corporation (NHK) on January 20, 2002.

The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.

The Near Infrared Spectrum of Miranda Evidence of Crystalline Water Ice

A spectrum from 1.2 to 2.5 μm of Uranus' small satellite Miranda obtained in June 1999 reveals strong water-ice signatures. It confirms the existence of a 2.0-μm water feature previously detected on Miranda and shows a strong second broad 1.5-μm water-ice absorption feature. The spectra also reveal a weak absorption band at 1.65 μm that is indicative of crystalline water ice. Reflectance models which combine the new spectra with new photometry indicate that the spectra are characteristic of a mostly water-ice surface, with a large fraction of carbonaceous or silicate contaminates, and the possible presence of ammonia hydrate, as implied by an apparent weak feature near 2.2 μm. The possible presence of other volatiles is also investigated

The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.

The photo shows Uranus surrounded by its rings and some of the moons, as they appear on a near-infrared image that was obtained in the Ks-band (at wavelength 2.2 µm) with the ISAAC multi-mode instrument on the 8.2-m VLT ANTU telescope at the ESO Paranal Observatory (Chile). The exposure was made on November 19, 2002 (03:00 hrs UT) during a planetary research programme. The observing conditions were excellent (seeing 0.5 arcsec) and the exposure lasted 5 min. The angular diameter of Uranus is about 3.5 arcsec.

An image of the planet Uranus (located 20 Astronomical units from Earth) obtained at the Very Large Telescope Observatory using the Adaptive Optics system NAOS and the near-infrared imager CONICA to capture high-contrast images of the giant planet and its system of satellites and rings during its 2008 equinox. Every 42 years, the ring (and satellites) plane of Uranus crosses the Sun, providing us with a unique opportunity to observe the rings while they present their edge to us. Ring plane crossing also allow us to observe the rings form their dark side (i.e. while the Sun is illuminating them from the opposite side), so one can search for faint satellites, faint rings, or faint ring structures, which could not be seen otherwise. Ring Plane Crossings are also an excellent opportunity to observe mutual events between satellites such as eclipse or occultation phenomena. The image above corresponds to a one minute exposure (maximum permitted time to prevent trailing of the moving satellites) obtained at 2.2 micron with a K band filter. The bandpass of this filter matches the absorption bands of methane, which is present in the atmosphere of Uranus, and has the effect of making the bright planet (almost) completely disappear from our images. Thanks to this observing trick, we can observe the faint rings and small satellites of Uranus, which would become invisible otherwise, lost in the glare of the planet. The bright spots on each side of Uranus are Miranda (~470km diam.) and Ariel (~1100km diam.), respectively to the right and left of the image. Two much smaller satellites can be seen just above the ring plane, to the left of the planet, the closer to Uranus being Puck (~150km diam.) and the other Portia (~100km), near the ring tip in this image. A movie of these observations is also available. The movie shows an animation of this system of satellites over a two hour period. You can easily see the impact of fluctuating seeing conditions on the image quality. Under good seeing, both small satellites Puck and Portia becomes clearly visible when they move along their orbital path, while the images start to blur when the seeing conditions degrade. Credit: C. Dumas, B. Sicardy, and J.-E. Arlot

The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.

The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.

The first image of Uranus snapped by a ground-based telescope—the W.M. Keck Observatory in Hawaii—shows for the first time the dusty rings edge-on to the Earth (bottom), offering a unique view of their dark side.

A series of previous Keck images (top) shows how astronomers' view of the rings has changed since 2004.

The new image shows that the rings' dust pattern has changed significantly since the 1980s, suggesting that Uranus has suffered occassional large impacts over the past 21 years.

Imke de Pater of the University of California, Berkeley, led a study of the image appearing this week in the online advance edition of the journal Science.

"We think that dusty rings in general are sustained by impacts," de Pater said. "The rings of Jupiter exist because small meteorites continuously bombard the moons in Jupiter's system."

Study co-author Heidi Hammel of the Space Science Institute in Ridgefield, Connecticut, added that Uranus has been "the unappreciated underdog of the outer solar system for too long.

"It is refreshing to see such dynamic change and exciting evolution in the rings and the planet."

Astronomers have captured their first glare-free glimpse of Uranus's rings since they were first photographed more than 20 years ago by the Voyager spacecraft.

The new pictures show in unprecedented detail the normally unlit side of the planet's rings and the dust that surrounds them. They might also reveal the presence of new Uranian moons. Normally, these features are obscured by glare from the micron-sized ring particles.

The images were snapped by ground and space telescopes as the planet's rings swiveled edge-on to Earth during a rare celestial alignment that occurs only once every 42 years.

Constantly changingThe photos also reveal that the pattern of dust surrounding the rings has changed greatly since they were first photographed by NASA's Voyager-2 spacecraft in 1986.

Back then, the dust appeared to be embedded in the rings. In images taken by the Keck II telescope in Hawaii on May 28, 2007, the dust appears as a broad cloud that encompasses nearly all of the planet's dozen or so rings.

"People tend to think of the rings as unchanging, but our observations show that not to be the case," said study leader Imke de Pater, an astronomer at the University of California, Berkeley.

In fact, one of the inner rings, called zeta, appears in the new images to be several thousand kilometers farther from the planet than when it was discovered by Voyager.

"The ring may have moved, or it may be an entirely new ring," said study team member Mark Sholwater of the SETI Institute in Mountain View, California.

Uranus' ring system is divided into 11 thin, dark rings. The cross-section below illustrates the ring system to scale (in terms of radial distance from the centre of Neptune). The ring system was discovered by accident on 10th March 1977, when Uranus occulted a star. Scientists planned to measure the diameter of Uranus accurately and also obtain data on its upper atmosphere. James Elliott and colleagues observed the event from high altitude in a NASA plane, and noticed the star blink several times shortly before and after the occultation. (Kaufmann, 1994.) It was clear that Uranus possessed a system of rings, and because of Uranus's unique 97.86° axial tilt, it was highly likely that the rings would be detected if they were present (because at the time, the full face of the ring system was directed towards Earth). (Diagram based on data from the NSSDC.)Rings 6, 5, 4, h and l average about 2 Km in width. The other rings' widths are listed below.

a : 4 - 10 Km b : 5 - 11 Km g : 1 - 4 Km d : 3 - 7 Km e : 20 - 96 Km

Of all of Uranus' satellites, only Cordelia orbits at distances similar to those of the rings, at around 50,000 Km from the centre of the planet. This is clearly within 2 radii of the centre of Uranus, and therefore well within its Roche limit. The fact that Cordelia is a small body only 26 Km across may account for why it remains a whole body and has not been torn apart by tidal forces. In addition, it must have a reasonably high tensile strength

The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.

It has been reported that the outermost ring of Uranus is blue, and it was probably created by a moon that orbits inside the ring. Along with a blue ring, a red outer ring has also been observed around Uranus. It has been known for some time now that Uranus has several inner rings that are of neutral color. The only planets with known blue rings are Uranus and Saturn. Both blue rings have moons orbiting just inside the rings. A team of researchers led by Imke de Pater, a professor of astronomy at the University of California, Berkeley, has a detailed report that will be published in tomorrow's edition of the journal Science. According to Space.com:

"The outer ring of Saturn is blue and has Enceladus right smack at its brightest spot, and Uranus is strikingly similar, with its blue ring right on top of Mab's orbit," said Imke de Pater, professor of astronomy at the University of California, Berkeley.

Rings in False Color The 9 main rings of Uranus are visible here as horizontal lines. The somewhat fainter, pastel lines seen between the rings are artifacts of computer enhancement. Six narrow-angle images were used to extract color information from the extremely dark and faint rings. The final image was made from three color averages and represents an enhanced, false-color view. The image shows that the brightest, or epsilon ring at top is neutral in color, with the fainter 8 remaining rings showing slight color differences between them.

Hubble Discovers Giant Rings and New Moons Encircling Uranus Even though the Voyager 2 spacecraft paid a close-up visit to Uranus in 1986, the distant planet continues revealing surprises to the eye of NASA's Hubble Space Telescope. Hubble’s high sensitivity and sharp view has uncovered a pair of giant rings girdling the planet. The largest is twice the diameter of the planet’s previously known ring system, first discovered in the late 1970s. Hubble also spied two small satellites, named Mab and Cupid. One of the satellites shares an orbit with the outermost of the new rings. The satellite is probably the source of fresh dust that keeps replenishing the ring with new material knocked off the satellite from meteoroid impacts. Without such replenishment, the dust in the ring would slowly spiral in toward Uranus. Collectively, these new discoveries mean that Uranus has a youthful and dynamic system of rings and moons. Because of the extreme tilt of Uranus's axis, the ring system appears nearly perpendicular relative to rings around other gas giant planets like Saturn. Also, unlike Saturn, the rings are very dark and dim because they are mostly dust rather than ice.

These near-infrared images of the planet Uranus were taken with the JPL Palomar Adaptive Optics (AO) System and the Cornell PHARO camera on August 1, 1999. The AO system was locked on the disk of the planet to produce about 0.25 arcsec angular resolution. At 1.2 and 1.6 microns, atmospheric features around the north pole and near the equator are visible. At 2.2 microns, methane absorption renders the disk of the planet almost invisible, although faint limb-brightening can be detected. The Uranian ring system and two moons: Miranda (magnitude ~15) and Puck (~19), are most easily visible in the 2.2 micron image where interference from the planet is minimal.

The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.

If springtime on Earth were anything like it will be on Uranus, we would be experiencing waves of massive storms, each one covering the country from Kansas to New York, with temperatures of 300 degrees below zero.

A dramatic new time-lapse movie by NASA's Hubble Space Telescope shows for the first time seasonal changes on the planet. Once considered one of the blander-looking planets, Uranus is now revealed as a dynamic world with the brightest clouds in the outer Solar System and a fragile ring system that wobbles like an unbalanced wagon wheel. The clouds are probably made of crystals of methane, which condense as warm bubbles of gas well up from deep in the atmosphere of Uranus.

The movie, created by Hubble researcher Erich Karkoschka of the University of Arizona, clearly shows for the first time the wobble in the ring system, which is made of billions of tiny pebbles. This wobble may be caused by Uranus' shape, which is like a slightly flattened globe, along with the gravitational tug from its many moons.

The seasonal changes on Earth are caused by our planet's rotational pole being slightly tilted. Consequently, the Earth's Southern and Northern hemispheres are alternately tipped toward or away from the Sun as the Earth moves around its orbit. Uranus is tilted completely over on its side, giving rise to extreme 20-year-long seasons and unusual weather. For nearly a quarter of the Uranian year, the sun shines directly over each pole, leaving the other half of the planet plunged into a long, dark, frigid winter.

The Northern Hemisphere of Uranus is just now coming out of the grip of its decades-long winter. As the sunlight reaches some latitudes, it warms the atmosphere. This appears to be causing the atmosphere to come out of a frigid hibernation and stir back to life. Uranus does not have a solid surface, but is instead a ball of mostly hydrogen and helium. Absorption of red light by methane in the atmosphere gives the planet its cyan color.

Uranus was discovered March 13, 1781, by William Herschel. Early visual observers reported Jupiter-like cloud belts on the planet, but when NASA's Voyager 2 flew by in 1986, Uranus appeared as featureless as a cue ball. In the past 13 years, the planet has moved far enough along its orbit for the sun to shine at mid-latitudes in the Northern Hemisphere. By the year 2007, the sun will be shining directly over Uranus' equator.

Two billion miles away in the atmosphere of Uranus, a dark vortex large enough to engulf two-thirds of the United States has appeared. Measuring 1,100 by 1,900 miles, the Hubble telescope captured images of the phenomenon which astronomers believe is a huge storm.

Previous Hubble images of Uranus taken over the last decade have shown no dark spot, leading astronomers to believe that the disturbance formed only very recently. Prior to Hubble, there were unconfirmed sightings of other dark spots on Uranus, including sketches made in the early 1900s, low-contrast Voyager spacecraft fly-by images in 1986, and near-infrared observations taken from a ground-based observatory in 1993.

While rare on Uranus, dark spots have been frequently observed on Neptune. It was believed that while Uranus is similar in size and atmospheric composition to Neptune, it did not have such an active atmosphere. Lawrence Sromovsky, who led the team that took the pictures, said that recently, however, Uranus's atmosphere had shown an unusual increase in activity.

The dark spot may be linked to the upcoming (2007) Uranian northern spring, when the sun will shine directly over the Uranian equator. "We have hypothesized that Uranus might become more Neptune-like as it approached its equinox," said team member Heidi B. Hammel. "The sudden appearance of this unusual dark feature suggests we might be right."

The disturbance was detected at a latitude of 27 degrees in Uranus's northern hemisphere, which is just now becoming fully exposed to sunlight after decades of being in shadow (Uranus takes 84 years to orbit the sun). How Uranus responds to seasonal sunlight changes is of great interest to astronomers as Uranus's sideways orientation (its rotation axis is tilted almost parallel to its orbital plane, such that the planet appears to be rotating on its side) could produce more unusual atmospheric phenomena.

The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.

The illusion from which we are seeking to extricate ourselves is not that constituted by the realm of space and time, but that which comes from failing to know that realm from the standpoint of a higher vision. -L.H.